This is very interesting. I suspect you used a pretty high quality video camera (compared to, say, an iPhone 6s). I have fooled around with using iPhone videos to track various thrown projectiles (such as an indoor (so as not to damage the walls) shot-put thrown in a racquet court . One annoying feature of the iPhone video is that successive frame images are sometimes exactly identical, which indicates that something anomalous occasionally occurs within the innards of the iPhone. I am interested in seeing how close the trajectories are to exact parabolas and understanding the inevitable deviations therefrom. Once again, thank you for an excellent post.